Centrifugal electric switch



Sept. 8, 1925.

H. '5. WHITE CENTRIFUGAL ELECTRIC SWITCH Filed NOV. 15, 1919 Inventor, Harold Elijah White Attorney? Patented Sept. 8 1925.

UNITED STATES PATENT OFFICE.

nnnonn ELIJAH WHITE, or mon'rcnam, NEW JERSEY, ASSIGNOB .ro caocxEa- WHEELER couranv, or AMPERE, NEW JEEsEY, A coaroaa'rron or NEW JEEsEr.

CENTBIFUGAL IEIJilG'JJBIC SWITCH.

Application filed November 15, 1919. .Serial No. 388,230.

i T 0 all whom it may concern Be it known that I, HAROLD ELIJAH WVHITE, a citizen of the United States of America, and a resident of Montclair, in the :ounty of Essex and State of New Jersey, have invented certain new and useful Improvements in Centrifugal Electric Switches, of which the followin is a specification.

Single phase in uction motors, to which this invention is especially applicable, comprise two windings, one of which is required to be energized only during starting and the circuit of which it is desirable to open when the motor has attained a certain speed. y

The object of this invention is to povide an automatically operated rugged and durable switch especially applicable for controlling this circuit, and to make it of such con struction that it may be housed within the frame of the motor and the contact ring thereof carried by the rotor shaft. Further objects are to provide for the maintaining of the electric circuit through contacts which do not slide on each other while carrying curent, but have a sufficient sliding contact during stopping to keep the contact surfaces in good condition. A further object is to provide for a quick opening of the contacts without chattering.

In the accompanyin sheet of drawings which forms a part of %his application Figure 1 is an end view of a switch embodymg this-invention, the end frame of the motor, with which it is used being omitted, and the contact supports and contact ring being partly broken away.

Figure 2 is a section t rough the'axis of the motor showing the contacts closed.

Figure 3 is a side view showing the contacts open.

Figure 4 is a diagram of the electrical circuits.

The switch is shown as applied to a single-phase motor with split-phase windings. The motor comprises a squirrelscage rotor 5 carried on a shaft 6, a power winding 7, and an auxiliary winding 8, used in starting, both of which derive energy from the same source of supply, as shown, by being directly connected through a connecting switch 9. The power winding is supplied with current both in starting and in running at full speed, and the auxiliary winding is energized in addition in starting but the circuit through it is broker'f when ,the motor is running above a certain speed in order to save current.

To automatically break this circuit through the auxiliary winding a centrifugally operated switch is provided. The switch comprises two elements one of which is a pair of contacts 10, 10 which are in the branch circuit through the auxiliary winding. The other element of the switch is a contact ring 11 which is mounted on an inthe switch and preferably the pair of contacts is mounted through insulating strips 13, 13 on the inner side of one of the end frames 14 of the motor, and the other element, preferably the contact ring, is carried by a revolving element of the motor, preferably the rotor shaft. The insulating disk which bears the contact ring is carried by a sliding sleeve 15, and the sliding sleeve is carried by the motor shaft, and slidable thereon. The sleeve has a shoulder 16 which forms a stop against which the disk carrying the contact ring bears when the switch is open, a spring 17 pressing the disk against this shoulder. When the switch is closed 'sulating disk 12. One of the elements of y this spring presses theoontact ring against the pair of contacts.

Centrifugal weights 18, 18 are guided on transverse pins 19. 19, and the pins are held by a bracket 20 which is attached to the rotor core by screws. The weights have a straights line movement only and a minimum of space needs to be provided between the squirrel cage and the end frame to afford them the necessary freedom. Oblique links 21, 21 connect the weights with the sliding sleeve. Tension springs 22, 22 draw the weights together. These springs are of light wire with coils originally wound close so that they are under considerable initial tenstrikes the insulating disk, and is therefore instantaneous and without chattering.

On closing the connecting switch, the motor being at rest, current will start to flow through both the power winding and the auxiliary winding, and the motor will start but the contact ring will not turn and Will bridge the pair of contacts and conduct current between them without rubbing. When a certain speed is reached the switch opens and the current continues only through the power winding. The centrifugal switch closes ordinarily only when the current has been cut off from the power winding and the motor is slowing down, and it follows that there will be no current flow throu h the centrifugal switch at the time of its 0 osing.

HAROLD ELIJAII \VH ITE. 

